Fix FK triggers losing DEFERRABLE/INITIALLY DEFERRED when marked ENFORCED again

Previously, a foreign key defined as DEFERRABLE INITIALLY DEFERRED could
behave as NOT DEFERRABLE after being set to NOT ENFORCED and then back
to ENFORCED.

This happened because recreating the FK triggers on re-enabling the constraint
forgot to restore the tgdeferrable and tginitdeferred fields in pg_trigger.

Fix this bug by properly setting those fields when the foreign key constraint
is marked ENFORCED again and its triggers are recreated, so the original
DEFERRABLE and INITIALLY DEFERRED properties are preserved.

Backpatch to v18, where NOT ENFORCED foreign keys were introduced.

Author: Yasuo Honda <yasuo.honda@gmail.com>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Discussion: https://postgr.es/m/CAKmOUTms2nkxEZDdcrsjq5P3b2L_PR266Hv8kW5pANwmVaRJJQ@mail.gmail.com
Backpatch-through: 18

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index c69c12dc014d7fae52cc5993cbb1f4bb264f86cb..dd00e36c69d87d85281fe237135d6eb1973d3a85 100644 (file)
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -12558,6 +12558,8 @@ ATExecAlterFKConstrEnforceability(List **wqueue, ATAlterConstraint *cmdcon,
                fkconstraint->fk_matchtype = currcon->confmatchtype;
                fkconstraint->fk_upd_action = currcon->confupdtype;
                fkconstraint->fk_del_action = currcon->confdeltype;
+               fkconstraint->deferrable = currcon->condeferrable;
+               fkconstraint->initdeferred = currcon->condeferred;
 
                /* Create referenced triggers */
                if (currcon->conrelid == fkrelid)

diff --git a/src/test/regress/expected/foreign_key.out b/src/test/regress/expected/foreign_key.out
index 9ae4dbf1b0a36ca218057ffb90eb03de4ce00f0d..4c69cb999cd0bfd789f184ec959b8216c6544331 100644 (file)
--- a/src/test/regress/expected/foreign_key.out
+++ b/src/test/regress/expected/foreign_key.out
@@ -1157,6 +1157,59 @@ INSERT INTO fktable VALUES (500, 1000);
 ERROR:  insert or update on table "fktable" violates foreign key constraint "fktable_fk_fkey"
 DETAIL:  Key (fk)=(1000) is not present in table "pktable".
 COMMIT;
+-- Check that the existing FK trigger is both deferrable and initially deferred
+SELECT conname, tgrelid::regclass as tgrel,
+       regexp_replace(tgname, '[0-9]+', 'N') as tgname, tgtype,
+       tgdeferrable, tginitdeferred
+FROM pg_trigger t JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+WHERE conrelid = 'fktable'::regclass AND conname = 'fktable_fk_fkey'
+ORDER BY tgrelid, tgtype;
+     conname     |  tgrel  |          tgname          | tgtype | tgdeferrable | tginitdeferred 
+-----------------+---------+--------------------------+--------+--------------+----------------
+ fktable_fk_fkey | pktable | RI_ConstraintTrigger_a_N |      9 | t            | t
+ fktable_fk_fkey | pktable | RI_ConstraintTrigger_a_N |     17 | t            | t
+ fktable_fk_fkey | fktable | RI_ConstraintTrigger_c_N |      5 | t            | t
+ fktable_fk_fkey | fktable | RI_ConstraintTrigger_c_N |     17 | t            | t
+(4 rows)
+
+-- Changing the constraint to NOT ENFORCED drops the associated FK triggers
+ALTER TABLE FKTABLE ALTER CONSTRAINT fktable_fk_fkey NOT ENFORCED;
+SELECT conname, tgrelid::regclass as tgrel,
+       regexp_replace(tgname, '[0-9]+', 'N') as tgname, tgtype,
+       tgdeferrable, tginitdeferred
+FROM pg_trigger t JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+WHERE conrelid = 'fktable'::regclass AND conname = 'fktable_fk_fkey'
+ORDER BY tgrelid, tgtype;
+ conname | tgrel | tgname | tgtype | tgdeferrable | tginitdeferred 
+---------+-------+--------+--------+--------------+----------------
+(0 rows)
+
+-- Changing it back to ENFORCED will recreate the necessary FK triggers
+-- that are deferrable and initially deferred
+ALTER TABLE FKTABLE ALTER CONSTRAINT fktable_fk_fkey ENFORCED;
+SELECT conname, tgrelid::regclass as tgrel,
+       regexp_replace(tgname, '[0-9]+', 'N') as tgname, tgtype,
+       tgdeferrable, tginitdeferred
+FROM pg_trigger t JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+WHERE conrelid = 'fktable'::regclass AND conname = 'fktable_fk_fkey'
+ORDER BY tgrelid, tgtype;
+     conname     |  tgrel  |          tgname          | tgtype | tgdeferrable | tginitdeferred 
+-----------------+---------+--------------------------+--------+--------------+----------------
+ fktable_fk_fkey | pktable | RI_ConstraintTrigger_a_N |      9 | t            | t
+ fktable_fk_fkey | pktable | RI_ConstraintTrigger_a_N |     17 | t            | t
+ fktable_fk_fkey | fktable | RI_ConstraintTrigger_c_N |      5 | t            | t
+ fktable_fk_fkey | fktable | RI_ConstraintTrigger_c_N |     17 | t            | t
+(4 rows)
+
+-- Verify that a deferrable, initially deferred foreign key still works
+-- as expected after being set to NOT ENFORCED and then re-enabled
+BEGIN;
+-- doesn't match PK, but no error yet
+INSERT INTO fktable VALUES (2, 20);
+-- should catch error from INSERT at commit
+COMMIT;
+ERROR:  insert or update on table "fktable" violates foreign key constraint "fktable_fk_fkey"
+DETAIL:  Key (fk)=(20) is not present in table "pktable".
 DROP TABLE fktable, pktable;
 -- tricky behavior: according to SQL99, if a deferred constraint is set
 -- to 'immediate' mode, it should be checked for validity *immediately*,

diff --git a/src/test/regress/sql/foreign_key.sql b/src/test/regress/sql/foreign_key.sql
index 3b8c95bf89366432b664e357ff5c3eaef56446f3..02a60d661a1bcb6dd1d5329c54af03e42f73cad1 100644 (file)
--- a/src/test/regress/sql/foreign_key.sql
+++ b/src/test/regress/sql/foreign_key.sql
@@ -784,6 +784,43 @@ INSERT INTO fktable VALUES (500, 1000);
 
 COMMIT;
 
+-- Check that the existing FK trigger is both deferrable and initially deferred
+SELECT conname, tgrelid::regclass as tgrel,
+       regexp_replace(tgname, '[0-9]+', 'N') as tgname, tgtype,
+       tgdeferrable, tginitdeferred
+FROM pg_trigger t JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+WHERE conrelid = 'fktable'::regclass AND conname = 'fktable_fk_fkey'
+ORDER BY tgrelid, tgtype;
+
+-- Changing the constraint to NOT ENFORCED drops the associated FK triggers
+ALTER TABLE FKTABLE ALTER CONSTRAINT fktable_fk_fkey NOT ENFORCED;
+SELECT conname, tgrelid::regclass as tgrel,
+       regexp_replace(tgname, '[0-9]+', 'N') as tgname, tgtype,
+       tgdeferrable, tginitdeferred
+FROM pg_trigger t JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+WHERE conrelid = 'fktable'::regclass AND conname = 'fktable_fk_fkey'
+ORDER BY tgrelid, tgtype;
+
+-- Changing it back to ENFORCED will recreate the necessary FK triggers
+-- that are deferrable and initially deferred
+ALTER TABLE FKTABLE ALTER CONSTRAINT fktable_fk_fkey ENFORCED;
+SELECT conname, tgrelid::regclass as tgrel,
+       regexp_replace(tgname, '[0-9]+', 'N') as tgname, tgtype,
+       tgdeferrable, tginitdeferred
+FROM pg_trigger t JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+WHERE conrelid = 'fktable'::regclass AND conname = 'fktable_fk_fkey'
+ORDER BY tgrelid, tgtype;
+
+-- Verify that a deferrable, initially deferred foreign key still works
+-- as expected after being set to NOT ENFORCED and then re-enabled
+BEGIN;
+
+-- doesn't match PK, but no error yet
+INSERT INTO fktable VALUES (2, 20);
+
+-- should catch error from INSERT at commit
+COMMIT;
+
 DROP TABLE fktable, pktable;
 
 -- tricky behavior: according to SQL99, if a deferred constraint is set